Transformer winding support



D. G. MGARN TRANSFORMER WINDING SUPPORT Filed Dec. 5, 19257 /MSI/l. A 77am /NS ULATIGN Ur..`,'.` 179 l l i l l l l l V l l l I l l L Patented Dec. 17, 1940 PATENT" OFFICE@ TRANSFRMER WINDING, SUPPORT Donald G. McAm, Pittsburgh, Pa., assignor'to` Allis-Chalmers'Manufacturing Company, Milwaukee, Wis., acm-poration of Delaware `Application December 3, 1937, Serial No. 177,932

2 claims.

This invention refers in general tosupports for electrical windings and particularly to supports for plural section windings providing definite insulated spaces into which coil sections can oe wound quickly and economically.

Supports or forms on which several sections of magnetizing windings have been wound have been molded from solid insulating material. This 1 machinery and simple changes in size and form were not easily made. `The, product, if made of synthetic materials of `high dielectric strength and oil resistivity, lacked flexibility and thereu fore was easily breakable. i

Pressed board and similar sheet insulating material havehigh dielectric strength at elevated temperatures. The dielectric strength of the ordinary moldable synthetic materials decreases m as the temperature is raised. Flexible sheet material is easily handled and can be stocked in rolls, thereby using little storage space. Its unit dielectric strength is high, thereby permitting, in transformer windings, the use of a thin insulating wall 25 between high and low voltage windings and consequently low reactance in the transformer. By utilizing such material for coil forms, it is a simple matter to change the size or number of coil section spaces.

so It is therefore an object of this invention to provide an improved winding support which avoids the above disadvantages and obtains th A above advantages. It is also an object of the present invention to 85 provide an improved support for plural section windings which will have sufficient rigidity to support the coil sections and will have sumcient ilexibility to avoid breakage.

It is also an object of this invention to provide a support made cheaply land economically from sheet insulating material.

It is a further object of the present invention to provide a support of the above type with immolding process required expensive molds and` (ci. y24e-iis) and bound together by a `binder such as shellac; Sheets of from twenty thousandths to y forty thousandths of an inch inthickness have been found satisfactory, however, the invention is not limited to a particular material or size. f 6 'I'he spool shown is formed by winding two layers 5 of sheet material on a cylindrical mandrel withasmall amount of shellac or similar binder betweenfthe layers to hold them in place on the mandrel. Several layers B of similar ma- 10 terial having longitudinal slits forming tabs 1 in each end thereof are then applied in a similar manner and the tabs 1 thereof bent at right Y angles to the longitudinal-axis ofthe spool and shellacked together. The exact width of the tabs l5 or end portions 1 depends upon the diameter of the spool, the width being such that a whole number of tabs 1 and a fractional tab 'l areincluded in a single layer B. Thus, in any layer 0 the slits between tabs 'l are staggered relative to the slits in the adjacent layer B. In other words, the slits in one layer 6 are adjacent approximately the center of a tab 1 in the adjacent layer '8. The depth of the slits is dependent upon 'desired depth 25 of the coil section.

Annular sheets 8 and 8 of thicker, more rigid insulating material are placed in the position shown and bound to the end por-tions 1 with shellac. 'I'he sheet s is placed immediately surso rounding and hush with ends of the innermost layers I.

One layer Il having end portions l2 and I3 between slits similar to those in the ends of layer l is thenapplied to the spool and the end portions l2 bent at right angles and bound to annular sheet l. Annular rings Il and I5 are then applied over the unbent end portions Il of layer Il and ring Il is bound to the bent portions I2, completing the assembling of one end of coil seco tion I0.

The end portions I3 are now bent and boundto ring I5 and ring II is applied and bound to portions Il.' A layer 2l, similar to layer Il, is similarly applied and the end portions 22 bound to 45 ring Il so that the slits therebetween are staggered relative to the slits between portions il of layer Il. Ring 23 is applied and bound, thereby completing the insulation between coil sections Iland 20. ,Coil sections I0 and 40 are similarly as- 50 sembled. As soon as the shellac has dried, the assembly becomes very rigid but with sumcient flexibility remaining to prevent breakage of the spool.

When used in transformer windings, the -high 55 voltage winding is wound in sections I0, 2U. 30 and l0 and the spool mounted on a core 4l having a low voltage winding 42 thereon wound to the diameter of the layer B. The end turns of coil section 20 are insulated from the adjacent end turns oi' coil section I0 by solid insulation oi rings I5, I8 and 2l. A long creepage voltage path is formed due to the staggering of adjacent end portions 22 and I3. The outer end portions of coil section I0 are similarly insulated from the outer end turns of the low voltage coil and from the core.

'I'he support above described incorporates in one spool, assembled from sheets of ilexible insulating material bound with shellac, the maior insulation between high and low voltage windings, between high voltage coil sections and between high voltage coil ends and the core. The coil section spaces are definite and rugged. It is obvious that changing the size of the spool, the number or depth oi sections, or the amount of any insulation, can be very simply effected by mere change in size of the sheets.

In winding the coil sections, end 33 of a conductor is inserted in hole 3| in the partition between coil sections l0 and 20 and end 34 of a conductor is inserted in a similar hole in the'partition between coil sections 30 and 40. Coil sections IU and 30 arethen wound simultaneously by rotating the spool in a given direction. The spool is then reversed on the mandrel, the ends of the conductor spliced to ends 33 and 34 in sections 2U and l0, and these sections then wound by rotating the spool in the same direction. This method permits of simple, extremely rapid, automatic machine winding. Any number of coil sections may be used and alternate sections wound simultaneously.

The end slits of the sheets 6 and H have been described and shown as longitudinal, however, these slits may be at an angle to the longitudinal axis if desired.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. A unitary plural section winding form comprising in combination, a ilrst cylindrical sheet of thin flexible insulating material provided at each end thereof with circumferentially spaced slits, means for rigidly maintaining the portions between said slits at substantially right angles to the longitudinal axis of said sheet to form end anges of said winding form, a plurality of additional cylindrical sheets o1' flexible insulating material each positioned on said first sheet and each provided at an end thereof with circumferentially spaced slits, and means for rigidly joining the portions between the slits of one additional sheet in staggered relation to portions between the slits of an adjacent additional sheet for maintaining said portions of said additional sheets at substantially right angles to said first Sheet to form a flange intermediate said end flanges and spaced therefrom, said joining means comprising a disk of sheet insulating material between said portions of said additional sheets, said joining means further comprising a binding material.

2. A unitary plural section winding form comprising in combination, a first cylindrical sheet of thin flexible insulating material provided at each end thereof with circumferentially spaced slits, means for rigidly maintaining the portions between said slits at substantially right angles to the longitudinal axis of said sheet to form end flanges of said winding form, a plurality of additional cylindrical sheets of flexible insulating material each positioned on said first sheet and each provided at both ends 'thereof with circumferentially spaced slits, and means for rigidly joining the portions between the slits of one additional sheet in staggered relation to portions between the slits of an adjacent additional sheet formaintaining said portions of said additional sheets at substantially right angles to said.rst sheet to form a flange intermediate said end flanges and spaced therefrom, said joining means comprising a disk of sheet insulating material between..said portions of said additional sheets, said Jolning means further comprising a binding material.

DONALD G. MCARN. 

